The invention relates to a system for light splitting particularly suitable for microscopic investigation of living tussues using the so called confocal or tandem scanning by a scanning disk with a number of spirally arranged elementary holes similar to a Nipkow disk where the investigated object is illuminated spot by spot from a light source through holes of a scanning disk and light reflected from the object passes through an elementary hole of the scanning disk situated with respect to the rotation axis of the scanning disk diametrically to the elementary hole of said disk, used for illumination of the object. A similar system is described in the British publication "Scanning" Vol. 7, pages 97 to 108 from 1985, and in U.S. Pat. No. 3,517,980 incorporated herein by reference.
Systems for light splitting applied for similar microscopes are usually provided with a prism with a semitransparent mirror coating. Other systems use a mirror with a semitransparent reflecting surface. In case prisms are applied, the contrast of the image is substantially reduced due to disturbing reflections. This drawback has been eliminated by application of a semi-transparent mirror of minute thickness. The technology and non uniformity of used materials for said mirrors reduced however the optical properties of systems provided with similar mirrors.
Both the prism with a semitransparent mirror coating and the semitransparent mirror are part of a system for light splitting provided with additional prisms or mirrors. Their mutual correct alignment and adjustment together with other optical elements are main requirements for a correct functioning of microscopes provided with said systems. The number of optical elements required for a thus arranged system for light splitting reduces the contrast of the resulting image and increases the possibility of some failure due to the number of components.
In some cases a prism is used for light splitting, to which the light for the investigated object is supplied in the shape of two pencils of rays by two tube lenses behind the objective. Pencils of rays leaving the prism are rectified by a couple of mirrors to the image plane provided with a Fresnel condensing lens and a diversion plate. A thus designed system for light splitting is part of a microscope for stereoscopic reproduction.